Abstract : This document is a manual to assist military and operations research analysts in the use of the COMMEL (communications-electronics) 2 Model and in the preparation of the input data base for the model. This manual was prepared by Evaluation Technologies, Incorporated (ETI) under contract to the US Army Concepts Analysis Agency (CAA) to document the COMMEL 2 Model, as improved by ETI; a CAA updating of the manual, where required, based on experience gained while using the model in early 1976 has been included in this edition of the document. The COMMEL 2 Model was an element of the CAA study Communications Operational Effectiveness Methodology. This study was an element of the Operational Effectiveness of Communications methodology development program sponsored by the Deputy Chief of Staff for Operations and Plans (DCSOPS). The COMMEL Model is a fully computerized combat simulation which includes dynamic interface between tactical operations and communications systems. The model output provides statistics on both communications system performance and combat outcome. The COMMEL Model simulates division-level combat with resolution to company level. Tactical and communications activities are represented by four interrelated submodels which periodically transmit event statistics to output files. The model is basically deterministic although message routing factors may be varied through use of random number generator. (Author)